The genetic and biochemical studies on ts110, a Moloney murine sarcoma virus (MSV) temperature-sensitive (ts) mutant which transforms cells at 34 but not at 39, have been extended. At least 0.3 X 10 to the 6 daltons of genetic information has been deleted from ts110 MSV, when compared to its wild type (wt) parent. Furthermore, ts110-transformed normal rat kidney cells contain an additional major RNA species approximately 0.6 X 10 to the six daltons smaller then the single major species found in wt-transformed cells.